2004 Tahoe LS 4WD

Hello,

Tahoe sat outside in the rain for a couple of nights and the battery was stone dead. Nothing was left on.

I swapped out the 0.00V stone dead battery for a charged battery. I left one cable off and used a multimeter set to 10 Amps DC to close the circuit as needed for testing.

First try with ignition off, it pulled 10+ amps current. I assume it was recharing some capacitors?

We pulled a few fuses and read 3.6V. Put them in one by one, and it stayed at 3.6V. So the 10+ amps was a one time thing. But still far too high, obviously.

Removing the LBEC 1 (50 Amp) fuse drops the drain from 3.6A to 1.6A. Left that one out.

Removing the IPC/DIC (10 Amp) fuse drops the drain from 1.6A to 1.1A. Still too high! Left that one out.

We removed EVERY other fuse--under hood panel, driver door dash side panel, drive left foot kick panel--the current never dropped below 1.1A.

Checked the wires feeding that kick panel, inspected the insulation, wiggled them... no change.

Unplugged the one car phone charger, so nothing in the front or rear cig plugs... no change.

Checked the trailer plug wiring, it's fine (shouldn't matter, all those fuses got pulled at one point or another).

What is going on here?

And what do those two fuse circuits do? I read the details on the LBEC but having pulled the other fuses am not having any light bulbs appear over my thick skull.

Thanks in advance.

 

I've found a couple of things that go into further detail.

Bulletin No.: 02-01-39-007B, which includes my 2004 Tahoe, says it can take up to 4-1/4 hours for some systems to go into sleep mode, and to wait at least 5 hours with the ammeter in place, doors closed, key off, before reading the "final" parasitic draw.

I will try that over the next few days.


Bulletin No. 02066 (further down the same page linked above) states: "An anomaly in the operation of the steering wheel position sensor may keep the Body Control Module (BCM) from shutting down when the key is in the "OFF" position. The resultant 3.5 amp draw/load on the battery could possibly discharge the battery to the point where the battery will not have sufficient amperage to start the vehicle."

That "3.5 amp draw/load" jumps out at me, because I am measuring a 3.6 amp draw.

I will leave the LBEC 1 (50 Amp) and IPC/DIC (10 Amp) fuses in, get the ammeter wired into the negative battery cable connection, give it 5 hours for everything to go to sleep, and see what draw I have.

If I still see about 3.5 amps, then it begins to sound like my BCM is not shutting down, the same problem as the 2003 model recalls--but my 2004 does not have such a recall. GM's solution for the 2003's was, "Dealers are to reprogram the BCM." If I would have to go that route, I suppose the dealership will hit me for about a grand for diagnosis, shop time and a new BCM (my warranty is long expired).

Is it possible to reprogram these things outside of a dealership, or has anyone bought one from an auto parts store or online (ebay, etc.)?

Thanks.

 

By the way, my last 8 digits of the VIN start with "4J", so a 2004 from Janesville, I guess. I guess the 2003 recall does not apply, though this seems so similar in terms of symptoms.

There are no aftermarket accessories at all. Nothing is plugged into the front or rear cig lighter ports.

One thing about the HVAC controls... for many years now the actuators under the dash "hunt"--they go "click click click", and I have to slide the heat controls up or down repeatedly until I find a spot where the "hunting" is quieter. I've tried looking at the actuators and tried one or two "recalibration" procedures but nothing worked. Of course, they don't click at all when the key is off.

Also, just this winter the heat started fading between warm and cold. I figure I'll be replacing the air mix actuator pretty soon, if that's the most likely culprit. I need to check for codes (they've all been cleared lately with the battery stone dead).

I suppose I should disconnect the alternator to check for bad diodes? Not sure how that relates to the LBEC 1 (50 Amp) and IPC/DIC (10 Amp) fuses changing the amp draw.

Should we pull each relay one at a time? We did all the fuses, but not all the relays.

This is a very frustrating problem. I've read forum posts of owners being charged more than $1,000 for the dealership troubleshooting and then fixing these symptoms.

 

Went out to set up for the 5 hour test. After just driving the truck, I had to disconnect the negative battery cable to set up the test. With all the fuses back in, I'm seeing 1.5 Amp draw (at the beginning of the 5 hour test), whereas the other day I saw 3.6 Amp. I have no idea why it's different now.

I will check the draw in 5 hours.

 

Pretty difficult to do, but I think we might have gotten a valid reading. I had the negative cable tied to the battery negative through a jumper cable. This way I was able to touch the ammeter to insert it into the circuit, then remove the jumper cable from the battery, so that I didn't have to leave the multimeter in series for 5 hours (I wasn't sure if a few amps for that long would be a problem for it--for example, it's rated for 10 Amps for 15 seconds max, then cool off for 15 minutes).

Anyway, I had the multimeter on the 10 Amp scale, because I had been seeing 1, 3, up to 10 Amps in the last few days. When I put it in series, I read 0.00 Amps. That doesn't make much sense, because that means less than .009 or .005 Amps, that is, 9 or 5 mA, when it should be 30 to 50 mA based on what I've read. So either everything went to sleep and the meter doesn't read low currents accurately on the 10 Amp scale, or I screwed up and didn't have a very good connection.

So then I pulled the meter probe away for one second and then retouched it--the current climbed quickly back to 1.5 Amp, like systems woke up due to breaking the circuit and then re-establishing it (battery removed and then back in). Or maybe I just didn't have good contact the first time, not sure.

I'm running out of ideas on this. I thought about checking each fuse for mV drop across the little metal tabs on the fuse top, but since we've pulled every fuse while watching current, I don't think I'll learn anything new.

I've got the spare battery installed now. I recharged the stone dead one (probably junk now) and have it in the back of the Tahoe, just in case. (My jumper box is in the trunk of my daughter's car off at college.)

The truck usually starts if it doesn't sit more than two days. We'll see.

What a horseschmitt design.

Any ideas?

Thanks.

 

Anyone?

 

Have you checked the battery?? I had a battery that held voltage fine, but failed load test at the parts store.

If battery is OK, you can also check the alternator...if it has dying insulation, it will drain your batter...

 

I just went thru the same problem of a parasitic draw with a 2003 Ford Taurus. I found out that it needed an hour for all current drawing systems to go to sleep. I also connected a jumper from the neg. battery to ground and also an ammeter. I made sure that the ammeter read some amperage (3.1 amps with the jumper disconnected. I then re-connected the jumper and did NOT disconnect the ammeter but simply turned it off while waiting for the systems to go to sleep. I would try your 5 hour test again and make sure the ammeter is making a good connection. I don't think pulling relays will help since they're all powered thru fuses. After you get an accurate amp reading after the 5 hour wait it might be under an amp and you didn't notice it going away when you pulled the fuses the last time. Any draw over 50 to 100 milliamps is going to quickly discharge a battery. I would now try pulling the fuses again while someone watches the meter. After you pull each fuse DONOT re-install it since you might power up some current drawing module.

 

jamurrin, it can't be the battery, because I see the drain with the main battery and with the spare battery, and I don't see how they could cause the drain. I haven't disconnected the alternator yet. It's about a year old.

Chuck, that sounds promising. But my ammeter is part of my multimeter. Turning it off means clicking through the ac volt scales. Also, I would start on the 10 amp scale. Dropping to a lower scale means pulling the lead to plug it into a different port on the multimeter, which would break the circuit. Did you use more of a dedicated ammeter?

Thanks.

 

I'm using a Fluke VOM. The selector **** is all the way counterclockwise for "off". The 10 amp scale requires the positive probe to be plugged into the jack marked "10 ams" and the **** turned all the way clockwise to the 10 amp scale. This creates NO problems when switching from "off" to "10 amps". Using a different type VOM without a separate jack for amperage shouldn't create any problems that I can think of. Keep the jumper connected while you switch from "on" to"off" or vv. Any reading on AC or DC voltage should be less than 0.5 volts if you have a good jumper connection. Ohms should read almost zero ohms. The low amperage scale should read only a few milliamps (same as the 10 amp scale). I would strongly suggest disconnecting the alternator. A failed (shorted) diode will cause a definite drain. If you want to switch amperage scales on your meter --simply re-connect the jumper before changing scales.